JDX files store language dictionaries used by Jspell, a simple online spell check software application.

JDX files are typically used by programs written in JAVA, AJAX, HTML, PHP, .NET Web Server, and other programming languages. JSpell was developed by Page Scholar. The functionality offered by JSpell heavily depend on implemented dictionaries. The basic version of Jspell offers English, French, Spanish, Italian, and German dictionaries.